1. Field of the Invention
The present invention relates to locks having electronic input means and methods of inputting lock combinations, primarily for safes and other secure containers.
2. Description of the Related Art
Safes and other secure containers have traditionally used combination locks for controlling and authorizing entry. Locks had been mechanical and relied on a person dialing a correct combination on a rotating dial. The rotation positioned mechanical elements within the lock such that dialing the correct combination allowed a locking bolt to release the container door. For example, traditional mechanical locks, such as Gartner, U.S. Pat. No. 3,968,667 (1976), rely on a dial rotating tumblers. Proper dial rotation aligns gates in the tumblers. Once the gates are aligned, a fence on a fence lever can enter the aligned gates. Continued rotation of the dial and tumblers pulls the fence lever and withdraws the bolt.
Electronics have replaced mechanical structures in many locks. Electronic locks can use electronics rather than aligned tumbler wheels to sense entry of the correct combination. The electronics can sense the rotary position of a combination lock dial, or a keypad can replace the combination dial. Consequently, instead of dialing a number, e.g., “72,” the user would first push the “7” and then the “2” keys for the same result. Uyeda, U.S. Pat. No. 5,134,870 (1992) and Gartner, U.S. Pat. No. 5,136,870 (1992) are examples of a keypad entry system for a safe and door lock, respectively.
When the lock is used to secure entry to a container, the electronic components are typically mounted on a housing inside the container door. The housing contains a battery and a circuit board, which contains the electronic circuitry controlling the lock. The keypad is on the outside of the housing so as to be accessible to the user. A cable typically extends between the keypad and the circuit board for transmitting signals between the two components.
Traditional electronic keypads generally include ten keys that correspond with the numbers “0” through “9.” One drawback of this type of traditional keypad design arises from the fact that as users repeatedly enter the correct, authorized access combination on the keypad, the keys representing correct numbers in the combination begin to show signs of visible wear. As a result, an unauthorized individual may figure out the correct access combination. To prevent this, the combination must periodically be changed such that each of the keys on the keypad are used at some point in time and, as a result, all keys show signs of wear. However, having to periodically change the correct, authorized access combination may create confusion for authorized users who must repeatedly remember new combinations.
Another drawback to traditional electronic locks having a display is that as the user enters the correct, authorized access combination, the access code may be visible to unauthorized users who thereafter may access the safe.
Thus, there is a need for an improved access combination system and method that may be accessed by a user while preventing unauthorized entry and maintaining a high level of security.